A Capture object is immutable and has no public constructor. Instances are returned through the CaptureCollection object, which is returned by the Match.Captures and Group.Captures properties. However, the Match.Captures property provides information about the same match as the Match object.

If you do not apply a quantifier to a capturing group, the Group.Captures property returns a CaptureCollection with a single Capture object that provides information about the same capture as the Group object. If you do apply a quantifier to a capturing group, the Group.Index, Group.Length, and Group.Value properties provide information only about the last captured group, whereas the Capture objects in the CaptureCollection provide information about all subexpression captures. The example provides an illustration.

The regular expression pattern ((\w+)[\s.])+ is defined as shown in the following table. Note that in this regular expression, a quantifier (+) is applied to the entire regular expression.

Pattern

Description

(\w+)

Match one or more word characters. This is the second capturing group.

[\s.])

Match a white-space character or period (".").

((\w+)[\s.])

Match one or more word characters followed by a white-space character or period ("."). This is the first capturing group.

((\w+)[\s.])+

Match one or more occurrences of a word character or characters followed by a white-space character or period (".").

In this example, the input string consists of two sentences. As the output shows, the first sentence consists of only one word, so the CaptureCollection object has a single Capture object that represents the same capture as the Group object. The second sentence consists of multiple words, so the Group objects only contain information about the last matched subexpression. Group 1, which represents the first capture, contains the last word in the sentence that has a closing period. Group 2, which represents the second capture, contains the last word in the sentence. However, the Capture objects in the group's CaptureCollection object capture each subexpression match. The Capture objects in the first capturing group's collection of captures contain information about each captured word and white-space character or period. The Capture objects in the second capturing group's collection of captures contain information about each captured word.